Combination preparation process and combination preparation system for zirconia and methylchlorosilane and/or polysilicon

ABSTRACT

Disclosed is a combined process for preparing zirconium oxide, methyl chlorosilane and/or polycrystalline silicon and a combined system comprising: preparing zirconium oxide by using zircon sand, carbon, chlorine gas, silicon, and hydrogen chloride as raw materials, the products separated during preparing zirconium oxide include gas phase products and liquid phase products, methyl chlorosilane is prepared from the gas phase separated during preparing zirconium oxide, and polycrystalline silicon is prepared by using the liquid phase products as raw materials. In this invention, not only carbon monoxide, hydrogen chloride and other waste gases generated are used as raw materials for producing methyl chlorosilane, but also a by-product silicon tetrachloride generated is used as a raw material for producing polycrystalline silicon, thereby effectively recycling waste gases and silicon tetrachloride, reducing the treatment cost of waste gases and silicon tetrachloride and the production cost of methyl chlorosilane and polycrystalline silicon, and avoiding environmental pollution.

This application claims the priority of Chinese Patent Application No.CN201811510146.5 filed on Dec. 11, 2018, with a title of “A CombinedProcess for Preparing Zirconium Oxide, Methyl Chlorosilane and/orpolycrystalline silicon, and a Combined System”, which is herebyincorporated by reference in its entirety.

FIELD OF THE INVENTION

The present invention belongs to the technical field for producingzirconium oxide and silicone monomers, and particularly relates to acombined process for preparing zirconium oxide, methyl chlorosilaneand/or polycrystalline silicon, and a combined system.

BACKGROUND OF THE INVENTION

Zirconium dioxide (ZrO₂) is an important ceramic material with excellentproperties such as high temperature resistance, wear resistance andcorrosion resistance. In addition to being used in refractory materialsand ceramic pigments, it has become an important raw material forelectronic ceramics, functional ceramics and artificial gemstones, andis increasingly widely used in high-tech fields. Zirconium tetrachlorideis a basic raw material for preparing zirconium oxide, and thepreparation process of zirconium tetrachloride is also a key step in thepreparation of zirconium oxide. A large amount of CO tail gas will begenerated during preparing zirconium tetrachloride by the chlorinationmethod. During the preparation process of zirconium oxide, a largeamount of waste acid solution will be generated, and the directdischarge will cause environmental pollution on the one hand, and wasteresources on the other hand.

SUMMARY OF THE INVENTION

In order to solve the above-mentioned defects in the prior art, thepresent disclosure provides a combined process for preparing zirconiumoxide and methyl chlorosilane and/or a polycrystalline silicon, and acombined system, the combined process can use waste gases such as carbonmonoxide and hydrogen chloride generated during preparing zirconiumoxide as raw materials for producing methyl chlorosilane, so as to allowthe waste gases to be effectively recycled with high value, whichfurther reduces the treatment cost of the waste gases and the productioncost of methyl chlorosilane. At the same time, silicon tetrachlorideliquid phase product generated during preparing zirconium oxide can alsobe used as a raw material for producing polycrystalline silicon.

In a first aspect, the present disclosure provides a combined processfor preparing zirconium oxide and methyl chlorosilane, comprising:

preparing zirconium oxide by using zircon sand, a reducing agent carbon,chlorine gas, a heat supplementing agent silicon and hydrogen chlorideas raw materials, and products separated during preparing zirconiumoxide include gas phase products and liquid phase products, and said gasphase products include carbon monoxide, hydrogen gas and hydrogenchloride; and

preparing methyl chlorosilane by using the separated gas phase productsduring preparing zirconium oxide as raw materials.

Preferably, the combined process specifically comprises the followingsteps:

mixing and heating zircon sand, the reducing agent carbon, chlorine gas,the heat supplementing agent silicon and hydrogen chloride in a firstreactor, wherein zircon sand, the reducing agent carbon and chlorine gasreact to generate zirconium tetrachloride, silicon tetrachloride andcarbon monoxide; the heat supplementing agent silicon, chlorine gas andhydrogen chloride react to generate silicon tetrachloride and hydrogengas, so as to yield a first gas phase mixture;

removing hydrogen chloride and chlorine gas from the first gas phasemixture by passing the first gas phase mixture through silicon powder ina dechlorinator;

cooling the first gas phase mixture from which hydrogen chloride andchlorine gas have been removed to separate a crude zirconiumtetrachloride solid; hydrolyzing the crude zirconium tetrachloride solidto generate zirconium oxychloride, so as to yield a hydrolysis mixture;then subjecting the hydrolysis mixture to evaporation, crystallizationand solid-liquid separation to yield solid zirconium oxychloride; andheating the solid zirconium oxychloride in a second reactor to yieldzirconium oxide;

scrubbing the first gas phase mixture from which the crude zirconiumtetrachloride solid has been removed by using silicon tetrachloride as ascrubbing solution to recovery silicon tetrachloride therein, so as toyield a second gas phase mixture comprising carbon monoxide and hydrogengas;

introducing the second gas phase mixture into a third reactor;pressurizing and heating to make reaction and generate methanol, so asto yield a third gas phase mixture;

introducing the third gas phase mixture into a fourth reactor, andintroducing hydrogen chloride into the fourth reactor, heating to makemethanol react with hydrogen chloride to generate methane chloride, soas to yield a fourth gas phase mixture;

introducing the fourth gas phase mixture into a fifth reactor, andintroducing silicon powder into the fifth reactor, heating to makemethane chloride react with the silicon powder to generate methylchlorosilane, so as to yield a fifth gas phase mixture.

Preferably, the combined process further comprises the following steps:

detecting a molar ratio of carbon to hydrogen in the gases introducedinto the third reactor by a hydrocarbon detector, when a detected molarratio of carbon to hydrogen is greater than a preset molar ratio ofcarbon to hydrogen, hydrogen gas is introduced into the third reactor,until the molar ratio of carbon to hydrogen in the gases introduced intothe third reactor is equal to the preset molar ratio of carbon tohydrogen; when a detected molar ratio of carbon to hydrogen is less thanthe preset molar ratio of carbon to hydrogen, amount of hydrogenchloride introduced into a first reactor is reduced, until the molarratio of carbon to hydrogen in the gases introduced into the thirdreactor is equal to the preset molar ratio of carbon to hydrogen.

Preferably, the preset molar ratio of carbon to hydrogen is 1:4 to 1:5.

Preferably, the third reactor has a pressure of 5.0 MPa to 6.0 MPa, anda heating temperature of 220° C. to 250° C.

Preferably, the combined process further comprises the following steps:

introducing one or more of the gas phase products produced byevaporation of the hydrolysis mixture and crystallization of thehydrolysis mixture into a stripping tower to stripe hydrogen chloride,and then the stripped hydrogen chloride is used as a source of hydrogenchloride for introducing into the fourth reactor.

Preferably, said stripping tower has a stripping temperature of 40° C.to 60° C., and a pressure of 0.1 MPa to 0.3 MPa.

Preferably, the combined process further comprises the following steps:

introducing gas phase products produced by evaporation of the hydrolysismixture into a heat exchanger as a heat source: introducing thehydrolysis mixture into the heat exchanger for raising temperature byheat exchange, then evaporating the hydrolysis mixture after raisingtemperature by heat exchange; introducing the gas phase productsproduced by evaporating the hydrolysis mixture into the heat exchangerfor lowering temperature by heat exchange, after that introducing thegas phase products into the stripping tower for stripping.

Preferably, the combined process further comprises the following steps:

cooling hydrogen chloride discharged from a gas phase outlet of thestripping tower to separate water therein, and introducing hydrogenchloride from which water has been removed into the fourth reactor.

Preferably, before subjecting the hydrolysis mixture to evaporation,crystallization, and solid-liquid separation to yield solid zirconiumoxychloride, the combined process further comprises the following steps:

subjecting the hydrolysis mixture to solid-liquid separation to removesolid impurities therein.

Preferably, before introducing the second gas phase mixture into thethird reactor, the combined process further comprises the followingsteps:

cooling the second gas phase mixture to separate silicon tetrachlorideliquid, so as to yield purified second gas phase products.

Preferably, the combined process further comprises the following steps:

the silicon tetrachloride liquid separated by cooling the second gasphase mixture is used as a cold source for the step of cooling andseparating the crude zirconium tetrachloride solid from the first gasphase mixture; and/or,

the silicon tetrachloride liquid separated by cooling the second gasphase mixture is used as a scrubbing solution for the step of scrubbingthe first gas phase mixture, from which silicon tetrachloride has beenseparated, to remove silicon tetrachloride.

Preferably, before introducing the third gas phase mixture into thefourth reactor, the combined process further comprises the followingsteps:

cooling the third gas phase mixture to yield crude methanol, andpurifying the crude methanol by rectification to yield purified thirdgas phase products.

Preferably, before introducing the fourth gas phase mixture into thefifth reactor, the combined process further comprises the followingsteps:

scrubbing and cooling the fourth gas phase mixture by using water as ascrubbing solution to remove methanol and hydrogen chloride, and thendrying to remove water, so as to yield purified fourth gas phaseproducts.

Preferably, the first reactor has a heating temperature of 1050° C. to1200° C., and/or the second reactor has a heating temperature of 800° C.to 1000° C.

Preferably, the fourth reactor has a heating temperature of 130° C. to150° C.

Preferably, the fifth reactor has a heating temperature of 280° C. to320° C.

Preferably, the combined process further comprises the following steps:

returning liquid produced by evaporation, crystallization andsolid-liquid separation of the hydrolysis mixture to the hydrolysismixture which is produced by hydrolyzing the crude zirconiumtetrachloride solid to generate zirconium oxychloride, and thensubjecting the hydrolysis mixture to evaporation, crystallization andsolid-liquid separation.

In a second aspect, the present disclosure also provides a combinedprocess for preparing zirconium oxide, methyl chlorosilane andpolycrystalline silicon, said liquid phase products separated during theabove-mentioned combined process for preparing zirconium oxide andmethyl chlorosilane comprises silicon tetrachloride, and said silicontetrachloride is used as a raw material to prepare polycrystallinesilicon.

Preferably, according to the above-mentioned combined process forpreparing zirconium oxide and methyl chlorosilane, it further comprisesthe following steps:

using silicon tetrachloride liquid phase products separated duringpreparing zirconium oxide as a raw material to prepare polycrystallinesilicon, which comprises firstly performing a hydrochlorination withsaid silicon tetrachloride to yield trichlorosilane, and then performinga hydrogen reduction reaction with the trichlorosilane to yieldpolycrystalline silicon.

In a third aspect, the present disclosure also provides a combinedsystem for preparing zirconium oxide and methyl chlorosilane used in theabove combined process, including:

a zirconium oxide preparation device, which is used to prepare zirconiumoxide with zircon sand, a reducing agent carbon, chlorine gas, a heatsupplementing agent silicon and hydrogen chloride as raw materials, andis also used to separate gas phase products of carbon monoxide, hydrogengas and hydrogen chloride produced during preparing zirconium oxide;

a methyl chlorosilane preparation device, which is connected with saidzirconium oxide preparation device, and is used to prepare methylchlorosilane with gas phase products of carbon monoxide, hydrogen gasand hydrogen chloride separated from said zirconium oxide preparationdevice as raw materials.

Preferably,

the zirconium oxide preparation device includes a first reactor, adechlorinator, a first cooling separator, a hydrolysis tank, anevaporator, a crystallizer, a first solid-liquid separator, a secondreactor, and a scrubbing tower,

the methyl chlorosilane preparation device includes a third reactor, afourth reactor, and a fifth reactor;

said first reactor is used to mix and heat zircon sand, a reducing agentcarbon, chlorine gas, a heat supplementing agent silicon, and hydrogenchloride, allow zircon sand, the reducing agent carbon, and chlorine gasto react to generate zirconium tetrachloride, silicon tetrachloride andcarbon monoxide; and allow the heat supplementing agent silicon,chlorine gas, hydrogen chloride to react to generate silicontetrachloride, hydrogen gas, so as to yield the first gas phase mixture;

said dechlorinator is arranged between said first reactor and said firstcooling separator, and said dechlorinator is connected with said firstreactor and said first cooling separator, respectively; alternatively,said dechlorinator is arranged in said first reactor, and separates afirst reaction chamber provided in the first reactor from outlet of thefirst reactor, and the dechlorinator is used to remove chlorine gas,hydrogen chloride in the first gas phase mixture by using silicon powertherein;

said first cooling separator is connected with said first reactor, andis used to cool the introduced first gas phase mixture from whichhydrogen chloride and chlorine have been removed, so as to separate thecrude zirconium tetrachloride solid and produce a first gas phasemixture without crude zirconium tetrachloride solid;

said hydrolysis tank is connected with said first cooling separator, andsaid crude zirconium tetrachloride solid is introduced into thehydrolysis tank and then is hydrolyzed to generate zirconiumoxychloride, so as to yield a hydrolysis mixture;

said evaporator is connected with said hydrolysis tank, and saidhydrolysis mixture is introduced into the evaporator for evaporation;

said crystallizer is connected with said evaporator, and the hydrolysismixture after evaporation is introduced into the crystallizer forcrystallization;

said first solid-liquid separator is connected with said crystallizer,and the hydrolysis mixture after crystallization is introduced into thefirst solid-liquid separator for solid-liquid separation, so as to yieldsolid zirconium oxychloride;

said second reactor is connected with said first solid-liquid separator,and solid zirconium oxychloride is introduced into the second reactorand heated to yield zirconium oxide;

said scrubbing tower is connected with said first cooling separator, andthe first gas phase mixture from which the crude zirconium tetrachloridesolid has been removed is scrubbed by using silicon tetrachloride as ascrubbing solution to recovery silicon tetrachloride liquid, so as toyield a second gas phase mixture comprising carbon monoxide and hydrogengas;

said third reactor is connected with said scrubbing tower, and saidsecond gas phase mixture is introduced into the third reactor, and ispressurized and heated to make the second gas phase mixture react andgenerate methanol, so as to yield the third gas phase mixture;

said fourth reactor is connected with said third reactor, said third gasphase mixture is introduced into the fourth reactor; hydrogen chlorideis introduced into the fourth reactor; and both of them is heated tomake methanol react with hydrogen chloride and to generate methanechloride, so as to yield a fourth gas phase mixture;

said fifth reactor is connected with said fourth reactor, said fourthgas phase mixture is introduced into the fifth reactor, silicon powderis introduced into the fifth reactor, and both of them is heated to makemethane chloride react with silicon powder and to generate methylchlorosilane, so as to yield a fifth gas phase mixture.

Preferably, the methyl chlorosilane preparation device furthercomprises:

a hydrogen pipeline connected with an inlet of said third reactor,wherein said hydrogen pipeline is used for introducing hydrogen into thethird reactor, and said hydrogen pipeline is provided with a firstvalve;

a hydrogen chloride pipeline connected with an inlet of said firstreactor, wherein said hydrogen chloride pipeline is used for introducinghydrogen chloride into the first reactor, and said hydrogen chloridepipeline is provided with a second valve;

a hydrocarbon detector for detecting the molar ratio of carbon tohydrogen in the gases introduced into said third reactor;

a controller for receiving a molar ratio value of carbon to hydrogen inthe gases in said third reactor detected by said hydrocarbon detector,when the molar ratio of carbon to hydrogen detected by the hydrocarbondetector is greater than a preset molar ratio of carbon to hydrogen, thecontroller open the first valve to introduce hydrogen gas into the thirdreactor, until the molar ratio of carbon to hydrogen in the gasesintroduced into the third reactor is equal to the preset molar ratio ofcarbon to hydrogen, and then the controller close the first valve; whenthe molar ratio of carbon to hydrogen detected by the hydrocarbondetector is less than the preset molar ratio of carbon to hydrogen, thecontroller close the second valve to reduce the amount of hydrogenchloride introduced into a first reactor, until the molar ratio ofcarbon to hydrogen in the gases introduced into the third reactor isequal to the preset molar ratio of carbon to hydrogen, and then thecontroller open the second valve.

Preferably, the methyl chlorosilane preparation device further includes:

a stripping tower, and a gas outlet of said stripping tower is connectedwith the inlet of said fourth reactor,

an inlet of said stripping tower is connected with said evaporator, andgas phase products evaporated by the evaporator is introduced into thestripping tower to strip hydrogen chloride, and the stripped hydrogenchloride is introduced into said fourth reactor as a source of hydrogenchloride; and/or,

the inlet of said stripping tower is connected with said crystallizer,and gas phase crystallized by the crystallizer is introduced into thestripping tower to strip hydrogen chloride, and the stripped hydrogenchloride is introduced into said fourth reactor as a source of hydrogenchloride.

Preferably, the methyl chlorosilane preparation device further includes:

a heat exchanger, which is connected with said stripping tower and alsoconnected with said evaporator, and the gas phase products produced byevaporating the hydrolysis mixture through the evaporator is introducedinto the heat exchanger as a heat source, and the hydrolysis mixture isintroduced into the heat exchanger for raising temperature by heatexchange, and then the gas phase products produced by evaporating thehydrolysis mixture are introduced into the heat exchanger for loweringtemperature by heat exchange, after that the gas phase products areintroduced into the stripping tower for stripping.

Preferably, the methyl chlorosilane preparation device further includes:

a cooling separator on the top of the stripping tower, wherein an inletof the cooling separator on the top of the stripping tower is connectedwith the gas outlet of the stripping tower, a liquid outlet of thecooling separator on the top of the stripping tower is connected withthe inlet on the top of the stripping tower, and a gas outlet of thecooling separator on the top of the tower is connected with said fourthreactor, and the cooling separator on the top of the stripping tower isused for cooling and separating water, and the cooled and separatedwater flows back into the stripping tower, and hydrogen chloride fromwhich water has been removed flows into the fourth reactor.

Preferably, said zirconium oxide preparation device further includes:

a second solid-liquid separator, wherein an inlet of said secondsolid-liquid separator is connected with an outlet of said hydrolysistank, an outlet of the second solid-liquid separator is connected withan inlet of said evaporator, and the hydrolysis mixture through thehydrolysis tank is introduced into the second solid-liquid separator forperforming solid-liquid separation to remove solid impurities, and thenflows into the evaporator.

Preferably, said zirconium oxide preparation device further includes:

a first cooler arranged between said scrubbing tower and said thirdreactor, wherein an inlet of said first cooler is connected with a gasoutlet of the scrubbing tower, a gas outlet of the first cooler isconnected with an inlet of the third reactor, and the first cooler isused for cooling the second gas phase mixture to separate the silicontetrachloride liquid, so as to yield purified second gas phase products.

Preferably, a liquid outlet of said first cooler is connected with theinlet of said first cooling separator, and the silicon tetrachlorideliquid separated from the second gas phase mixture is introduced intothe first cooling separator as a cold source to cool the first gas phasemixture to separate the crude zirconium tetrachloride solid; and/or,

a liquid outlet of said first cooler is connected with an scrubbingsolution inlet of the scrubbing tower, and the silicon tetrachlorideliquid separated by cooling the second gas phase mixture is introducedinto the scrubbing tower for scrubbing to recover the silicontetrachloride.

Preferably, said methyl chlorosilane preparation device furtherincludes:

a second cooler connected with said third reactor, wherein the third gasphase mixture enters said second cooler for cooling to yield crudemethanol;

a rectification tower arranged between said second cooler and saidfourth reactor, wherein the rectification tower is connected with thesecond cooler and the fourth reactor respectively, and crude methanol isintroduced into the rectification tower for purification to yieldpurified third gas phase products.

Preferably, said methyl chlorosilane preparation device furtherincludes:

a scrubbing and cooling tower connected with said fourth reactor,wherein the fourth gas phase mixture enters said scrubbing and coolingtower and uses water as a scrubbing solution to scrubbing and cool toremove methanol and hydrogen chloride;

a drying tower arranged between said scrubbing and cooling tower andsaid fifth reactor, wherein the drying tower is used to dry and removethe by-product dimethyl ether during reaction of water, methanol andhydrogen chloride for generating methyl chlorosilane, so as to yieldpurified fourth gas phase products.

Preferably, a liquid outlet of said first solid-liquid separator isconnected with an inlet of said hydrolysis tank, and the liquid in thefirst solid-liquid separator flows into the hydrolysis tank.

In a fourth aspect, the present disclosure also provides a combinedsystem for preparing zirconium oxide, methyl chlorosilane andpolycrystalline silicon, besides the system used for the combinedprocess for preparing zirconium oxide and methyl chlorosilane used inthe above process, it further includes:

a polycrystalline silicon preparation device, which is connected withsaid zirconium oxide preparation device and is used for preparingpolycrystalline silicon by using the silicon tetrachloride separated bysaid zirconium oxide preparation device as a raw material.

Compared with the prior art, the present disclosure has the followingbeneficial effects:

With the combined process for preparing zirconium oxide, methylchlorosilane and polycrystalline silicon, and the combined systemprovided in the present disclosure, not only carbon monoxide, hydrogenchloride and other waste gases generated during preparing zirconiumoxide are used as raw materials for producing methyl chlorosilane, butalso silicon tetrachloride, a by-product generated during preparingzirconium oxide, is used as a raw material for producing polycrystallinesilicon, so that both waste gases and silicon tetrachloride can beeffectively recycled with high value, which reduces the treatment costof waste gases and silicon tetrachloride, avoids environmentalpollution, reduces the production cost of methyl chlorosilane andpolycrystalline silicon, and improves the technological level as well asthe comprehensive economic benefits.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic structural diagram of the combined system forpreparing zirconium oxide, methyl chlorosilane and/or polycrystallinesilicon provided in Example 2 of the present disclosure;

FIG. 2 is a schematic structural diagram of the combined system forpreparing zirconium oxide and methyl chlorosilane and/or polycrystallinesilicon provided in Example 3 of the present disclosure;

FIG. 3 is a flow chart of the combined process for preparing zirconiumoxide, methyl chlorosilane and/or polycrystalline silicon provided inExample 2 of the present disclosure.

In the figures: 1—first reactor; 2—first cooling separator; 3—hydrolysistank; 4—evaporator; 5—crystallizer; 6—first solid-liquid separator;7—second reactor; 8—scrubbing tower; 9—third reactor; 10—fourth reactor;11—fifth reactor; 12—third cooler; 13—third storage tank; 14—hydrogengas pipeline; 15—hydrocarbon detector; 16—first valve; 17—strippingtower; 18—heat exchanger; 19—stripping tower kettle reboiler; 20—secondsolid-liquid separator; 21—first cooler; 22—first storage tank; 23—firsttransfer pump; 24—compressor; 25—second cooler; 26—rectification tower;27—second storage tank; 28—second transfer pump; 29—scrubbing andcooling tower; 30—drying tower; 31—heater; 32—beater; 33—centrifugalseparator; 34—cooling separator on the top of stripping tower;35—dechlorinator; 36—first reaction chamber; 37—outlet of the firstreactor; 38—hydrogen chloride pipeline; 39—inlet of the first reactor;40—second valve.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In order to make those skilled in the art better understand thetechnical solutions of the present disclosure, the present disclosurewill be further described in detail below with reference to theaccompanying drawings and examples.

Examples of the present invention are described in detail below,examples of which are illustrated in the accompanying drawings, whereinthe same or similar reference numerals refer to the same or similarelements or elements having the same or similar functions throughout.The examples described below with reference to the accompanying drawingsare exemplary and are only used to explain the present invention, butshould not be construed as a limitation on the present invention.

Example 1

The example of the present disclosure provides a combined system forpreparing zirconium oxide and methyl chlorosilane, comprising:

a zirconium oxide preparation device, which is used to prepare zirconiumoxide with zircon sand, a reducing agent carbon, chlorine gas, a heatsupplementing agent silicon and hydrogen chloride as raw materials, andthe zirconium oxide preparation device is also used to separate gasphase products of carbon monoxide, hydrogen gas and hydrogen chlorideproduced during preparing zirconium oxide;

a methyl chlorosilane preparation device, which is connected withzirconium oxide preparation device, and is used to prepare methylchlorosilane with gas phase products of carbon monoxide, hydrogen gasand hydrogen chloride separated from zirconium oxide preparation deviceas raw materials.

The example of the present disclosure also provide a combined processfor preparing zirconium oxide and methyl chlorosilane using theabove-mentioned combined system for preparing zirconium oxide and methylchlorosilane, comprising:

preparing zirconium oxide by using zircon sand, a reducing agent carbon,chlorine gas, a heat supplementing agent silicon and hydrogen chlorideas raw materials, gas phase products separated during preparingzirconium oxide include gas phase products of carbon monoxide, hydrogengas and hydrogen chloride; and

preparing methyl chlorosilane by using the separated gas phase productsduring preparing zirconium oxide as the raw materials.

In the example of the present disclosure, carbon monoxide and hydrogenchloride generated during preparing zirconium oxide are used as rawmaterials for producing methyl chlorosilane, so that both waste gasesand silicon tetrachloride can be effectively recycled with high value,which reduces the treatment cost of waste gases and silicontetrachloride, avoids environmental pollution, reduces the productioncost of methyl chlorosilane and polycrystalline silicon, and improvesthe technological level as well as the comprehensive economic benefits.

Example 2

As shown in FIG. 1 , an example of the present disclosure provides acombined system used for the combined process for preparing zirconiumoxide and methyl chlorosilane, comprising:

a zirconium oxide preparation device, which is used to prepare zirconiumoxide with zircon sand, a reducing agent carbon, chlorine gas, a heatsupplementing agent silicon and hydrogen chloride as raw materials, andthe zirconium oxide preparation device is also used to separate gasphase products of carbon monoxide, hydrogen gas and hydrogen chlorideproduced during preparing zirconium oxide;

a methyl chlorosilane preparation device, which is connected withzirconium oxide preparation device, and is used to prepare methylchlorosilane with gas phase products of carbon monoxide, hydrogen gasand hydrogen chloride separated from zirconium oxide preparation deviceas raw materials

Furthermore, the zirconium oxide preparation device in the presentexample includes: a first reactor 1, a dechlorinator 35, a first coolingseparator 2, a hydrolysis tank 3, an evaporator 4, a crystallizer 5, afirst solid-liquid separator 6, a second reactor 7 and a scrubbing tower8.

Zircon sand, the reducing agent carbon, chlorine gas, the heatsupplementing agent silicon and hydrogen chloride are mixed and heatedin the first reactor 1, wherein zircon sand, the reducing agent carbonand chlorine gas react to generate zirconium tetrachloride, silicontetrachloride and carbon monoxide; the heat supplementing agent silicon,chlorine gas and hydrogen chloride react to generate silicontetrachloride and hydrogen gas, so as to yield a first gas phasemixture;

Specifically, the first reactor 1 is provided with one or more gasinlet(s) for introducing chlorine gas and hydrogen chloride. The firstreactor 1 is also provided with one or more feeding port(s) for addingzircon sand, the reducing agent carbon, and the heat supplementing agentsilicon. In the present example, the interior of the first reactor 1includes a first reaction chamber 36, and the first reaction chamber 36is preferably disposed at the lower portion of the interior of the firstreactor 1. The first reactor 1 should also have heating function forheating the first reaction chamber 36, and has a heating temperature of1050° C. to 1200° C.

The dechlorinator 35 is arranged in the first reactor 1, and separatesthe first reaction chamber 36 provided the first reactor 1 from anoutlet 37 of the first reactor. The dechlorinator 35 is provided withsilicon powder to remove chlorine gas and hydrogen chloride in the firstgas phase mixture by passing the first gas phase mixture through siliconpowder in a dechlorinator 35.

The first cooling separator 2 is connected with the first reactor 1, andis used to cool the introduced first gas phase mixture from whichhydrogen chloride and chlorine gas have been removed, so as to separatecrude zirconium tetrachloride solid and produce a first gas phasemixture without crude zirconium tetrachloride solid; the tower top ofthe first cooling separator 2 is provided with a first temperaturedetection device and a first reflux scrubbing solution flow controldevice, the first temperature detection device and the first refluxscrubbing solution flow control device are connected in a cascade loopto control the first cooling separator to maintain an appropriatecooling temperature. In the present example, the first cooling separator2 preferably has a heating temperature of 180° C. to 250° C.

The hydrolysis tank 3 is connected with the first cooling separator 2,and crude zirconium tetrachloride solid is introduced into thehydrolysis tank 3 and then is hydrolyzed to generate zirconiumoxychloride, so as to yield a hydrolysis mixture. In the presentexample, the hydrolysis tank 3 is made of graphite.

The evaporator 4 is connected with the hydrolysis tank 3, and thehydrolysis mixture is introduced into the evaporator 4 for evaporation.In the present example, the evaporator 4 is made of graphite.

The crystallizer 5 is connected with the evaporator 4, and thehydrolysis mixture after evaporation is introduced into the crystallizer5 for crystallization. In the present example, the crystallizer 5 ismade of glass lining material.

The first solid-liquid separator 6 is connected with the crystallizer 5,and the hydrolysis mixture after crystallization is introduced into thefirst solid-liquid separator 6 for solid-liquid separation, so as toyield solid zirconium oxychloride; Specifically, the solid-liquidseparator 6 in the present example is a belt filter, preferably, thebelt filter is a vacuum belt filter.

The second reactor 7 is connected with the first solid-liquid separator6, and solid zirconium oxychloride is introduced into the second reactor7 and heated to yield zirconium oxide. In the present example, thesecond reactor 7 may have a heating temperature of 800° C. to 1000° C.

The scrubbing tower 8 is connected with the first cooling separator 2,and the first gas phase mixture from which the crude zirconiumtetrachloride solid has been removed is introduced into the scrubbingtower 8, then it is scrubbed by using silicon tetrachloride as ascrubbing solution to recovery silicon tetrachloride liquid, so as toyield a second gas phase mixture comprising carbon monoxide and hydrogengas. In the present example, the scrubbing tower 8 is a sieve traytower, and the scrubbing tower 8 preferably adopts silicon tetrachlorideas a scrubbing solution. The top of the scrubbing tower 8 is providedwith a second temperature detection device and a second scrubbingsolution flow control device, and the second temperature detectiondevice and the second scrubbing solution flow control device areconnected in a cascade loop to control the scrubbing tower 8 to maintainan appropriate cooling temperature. In the present example, thescrubbing tower 8 preferably has a heating temperature of −15° C. to 5°C.

Furthermore, the methyl chlorosilane preparation device in the presentexample mainly includes: a third reactor 9, a fourth reactor 10, and afifth reactor 11.

The third reactor 9 is connected with the scrubbing tower 8, and thesecond gas phase mixture is introduced into the third reactor 9, and ispressurized and heated to make the second gas phase mixture react andgenerate methanol, so as to yield a third gas phase mixture. In thepresent example, the third reactor 9 should have heating andpressurization functions, and the third reactor 9 may have a heatingtemperature of 220° C. to 250° C., and a pressure of 5.0 MPa to 6.0 MPa.

The fourth reactor 10 is connected with the third reactor 9. The thirdgas phase mixture is introduced into the fourth reactor 10 and hydrogenchloride is introduced into the fourth reactor 10, both of them areheated to make methanol react with hydrogen chloride to generate methanechloride, so as to yield a fourth gas phase mixture. In the presentexample, fourth reactor 10 may have a heating temperature of 130° C. to150° C.

The fifth reactor 11 is connected with the fourth reactor 10. The fourthgas phase mixture is introduced into the fifth reactor 11, and siliconpowder is introduced into the fifth reactor, both of them are heated tomake methane chloride react with silicon powder to generate methylchlorosilane, so as to yield a fifth gas phase mixture. Specifically,the fifth reactor 11 is a fluidized bed reactor, and may have a heatingtemperature of 280° C. to 320° C.

Specifically, the methyl chlorosilane preparation device in the presentexample further includes:

a third cooler 12, which is connected with the fifth reactor 11, and thethird cooler 12 is used for cooling a fifth gas phase mixture outputfrom the fifth reactor 11 into a liquid;

a third storage tank 13, which is connected with the third cooler 12,and the third storage tank 13 is used for storing the left liquid aftercooling by the third cooler 12, and the liquid is methyl chlorosilane.

It should be noted that, the methyl chlorosilane preparation device inthe present example further includes:

a hydrogen pipeline 14 connected with an inlet of the third reactor 9,and is used for introducing hydrogen gas into the third reactor 9, andthe hydrogen pipeline 14 is provided with a first valve 16;

a hydrogen chloride pipeline 38 connected with an inlet 39 of the firstreactor, and is used for introducing hydrogen chloride into the firstreactor 1, and hydrogen chloride pipeline 38 is provided with a secondvalve 40;

a hydrocarbon detector 15, preferably arranged between the scrubbingtower 8 and the third reactor 9, which is used to detect the molar ratioof carbon to hydrogen in the gases introduced into the third reactor 9,and transmit the detected a molar ratio value of carbon to hydrogen;

a controller electrically connected to the hydrocarbon detector, and isused for receiving the molar ratio value of carbon to hydrogen in thegases that is introduced into the third reactor 9 detected by thehydrocarbon detector 15, and the controller is also electricallyconnected with the above-mentioned first valve and the above-mentionedsecond valve; the molar ratio value of carbon to hydrogen is preset inthe controller, and the molar ratio value of carbon to hydrogen detectedby the hydrocarbon detector is compared with preset value by thecontroller; when the molar ratio of carbon to hydrogen detected by thehydrocarbon detector is greater than a preset molar ratio of carbon tohydrogen, the controller open the first valve 16 to introduce hydrogengas into the third reactor 9, until the detected molar ratio of carbonto hydrogen is equal to the preset molar ratio of carbon to hydrogen,and then the controller close the first valve 16; when the molar ratioof carbon to hydrogen detected by the hydrocarbon detector is less thanthe preset molar ratio of carbon to hydrogen, the controller close thesecond valve 40 to reduce the amount of hydrogen chloride introducedinto the first reactor 1, until the detected molar ratio of carbon tohydrogen is equal to the preset molar ratio of carbon to hydrogen, andthen the controller open the second valve 40.

Preferably, the combined system for preparing zirconium oxide and methylchlorosilane in the present example further includes:

a stripping tower 17, a gas outlet of the stripping tower 17 isconnected with an inlet of the fourth reactor 10,

the inlet of the stripping tower 17 is connected with the evaporator 4,and gas phase products evaporated by the evaporator 4 are introducedinto the stripping tower 17 to strip hydrogen chloride, and the strippedhydrogen chloride is introduced into the fourth reactor 10 as a sourceof hydrogen chloride; and/or;

the inlet of stripping tower 17 is connected with the crystallizer 5,and gas phase products crystallized by the crystallizer 5 are introducedinto the stripping tower 17 to strip hydrogen chloride, and the strippedhydrogen chloride is introduced into fourth reactor 10 as a source ofhydrogen chloride.

It should be noted that, the combined system for preparing zirconiumoxide and methyl chlorosilane in the present example further includes:

a stripping tower 17, a gas outlet of the stripping tower 17 isconnected with the inlet of the fourth reactor 10,

the inlet of the stripping tower 17 is connected with the evaporator 4,and gas phase products evaporated by the evaporator 4 are introducedinto the stripping tower 17 to strip hydrogen chloride, and the strippedhydrogen chloride is introduced into the fourth reactor 10 as a sourceof hydrogen chloride; and/or;

the inlet of stripping tower 17 is connected with the crystallizer 5,and gas phase products crystallized by the crystallizer 5 are introducedinto the stripping tower 17 to strip hydrogen chloride, and the strippedhydrogen chloride is introduced into fourth reactor 10 as a source ofhydrogen chloride; and

a liquid outlet of the stripping tower 17 is connected with an inlet ofthe hydrolysis tank 3, and waste liquid in the stripping tower 17 issupplemental flowed to the hydrolysis tank 3 as water for hydrolysis,which can reduce the used amount of water for hydrolysis in thehydrolysis tank 3.

It should be noted that, the methyl chlorosilane preparation device inthe present example further includes:

a heat exchanger 18, which is connected with stripping tower 17 and alsoconnected with evaporator 4, and the gas phase products produced byevaporating the hydrolysis mixture in the evaporator 4 are introducedinto the heat exchanger 18 as a heat source, and the hydrolysis mixtureis introduced into the heat exchanger 18 for raising temperature by heatexchange, and then the hydrolysis mixture after raising temperature byheat exchange is introduced into the evaporator 4 for evaporation, andthen the gas phase products produced by evaporating the hydrolysismixture in the in the evaporator 4 are introduced into the heatexchanger 18 for lowering temperature by heat exchange, after that thegas phase products are introduced into the stripping tower 17 forstripping.

Specifically, the heat exchanger 18 is used to recover the heat of thegas phase produced in the evaporator and to preheat the hydrolysismixture output from the hydrolysis tank. The heat exchanger 18 includesa cold source inlet, a cold source outlet, a heat source inlet and aheat source outlet, wherein: the cold source inlet is connected with theoutlet of the hydrolysis tank, and the cold source outlet is connectedwith the inlet of the evaporator, while the heat source inlet isconnected with the gas outlet of the evaporator, and the outlet of theheat source is connected with the inlet of the stripping tower. The gasphase products produced by evaporating in the evaporator 4 areintroduced into the heat exchanger as a heat source via the heat sourceinlet, and the hydrolysis mixture obtained from the hydrolysis tank 3 isintroduced into the heat exchanger 18 via the cool source inlet forraising temperature by heat exchange with the above-mentioned heatsource (i.e. phase products produced by evaporating in the evaporator4), and then the hydrolysis mixture after raising temperature by heatexchange through the heat exchanger 18 is introduced into the evaporator4 for evaporation, the gas phase products produced by evaporating in theevaporator 4 are introduced into the heat exchanger 18 for lowering thetemperature by heat exchange with the above hydrolysis mixtureintroduced into the heat exchanger by the hydrolysis tank 3, then itbecomes a gas-liquid mixture. The gas-liquid mixture is then introducedinto the stripping tower 17 for stripping via the heat source inlet. Inthe present example, the heat exchanger 18 is a shell-and-tube heatexchanger 18, and the heat exchanger 18 is made of graphite.

Specifically, the methyl chlorosilane preparation device in the presentexample further includes:

a stripping tower kettle reboiler 19 connected with the stripping tower17, and the stripping tower kettle reboiler 19 is used for heating thetower bottoms of the stripping tower 17. Specifically, an inlet of thestripping tower kettle reboiler 19 is connected with an outlet of thetower kettle of the stripping tower, and a gas outlet of the strippingtower kettle reboiler 19 is connected with an inlet of the strippingtower, so as to return gasification products to the stripping tower forstripping again. A liquid outlet of the stripping tower kettle reboiler19 and/or the stripping tower is connected with the hydrolysis tank 3,and is used to allow waste liquid in the stripping tower kettle reboiler19 and/or the stripping tower supplemental flowing to the hydrolysistank 3, so as to use as water for hydrolysis, thereby the usage amountof water for hydrolysis in the hydrolysis tank 3 can be reduced.

It should be noted that the zirconium oxide preparation device in thepresent example further includes:

a second solid-liquid separator 20, an inlet of second solid-liquidseparator 20 is connected with an outlet of hydrolysis tank 3, an outletof the second solid-liquid separator 20 is connected with an inlet ofevaporator 4, and the hydrolysis mixture through the hydrolysis tank 3is introduced into the second solid-liquid separator 20 for performingsolid-liquid separation to remove solid impurities, and then flows intothe evaporator 4. Specifically, the second solid-liquid separator 20 inthe present example is a filter press, and the filter press is made ofFRPP (i.e., glass fiber reinforced polypropylene pipe).

Specifically, the zirconium oxide preparation device in the presentexample further includes:

a first cooler 21, which is arranged between the scrubbing tower 8 andthe third reactor 9, an inlet of the first cooler 21 is connected with agas outlet of the scrubbing tower 8, a gas outlet of the first cooler 21is connected with an inlet of the third reactor 9, and the first cooler21 is used for cooling the second gas phase mixture output from thescrubbing tower 8 to separate (or in other words, precipitate) thesilicon tetrachloride liquid, so as to yield purified second gas phaseproducts. In the present example, the first cooler 21 is a tubular heatexchanger.

In the present example, a liquid outlet of first cooler 21 is connectedwith the inlet of first cooling separator 2, and the silicontetrachloride liquid separated from the second gas phase mixture isintroduced into the first cooling separator 2 as a cold source to coolthe first gas phase mixture, so as to separate the crude zirconiumtetrachloride solid; and/or,

a liquid outlet of first cooler 21 is connected with an inlet of thescrubbing tower 8, and the silicon tetrachloride liquid separated bycooling the second gas phase mixture is introduced into the scrubbingtower 8 for scrubbing to remove or recover metal chloride impuritiessuch as silicon tetrachloride in the second gas phase mixture.

Specifically, the combined system for preparing zirconium oxide andmethyl chlorosilane in the present example further includes:

a first storage tank 22, the inlet of the first storage tank 22 isconnected with the outlet of the first cooler 21, the first storage tank22 is used to store the silicon tetrachloride liquid separated by thefirst cooler 21, a part of the silicon tetrachloride liquid in the firststorage tank 22 flows into a first transfer pump 23, which can then beused as a cold source for the first cooler 2, and/or used as a scrubbingsolution of the scrubbing tower 8, and the other part flows out forsubsequent process, for example, polysilicon production process, that isto say, the first storage tank 22 can also be connected with apolycrystalline silicon preparation device, such as a hydrochlorinationreactor.

a first transfer pump 23, an inlet of the first transfer pump 23 isconnected with an outlet of the first storage tank 22, an outlet of thefirst transfer pump 23 is connected with an outlet of the scrubbingtower 8, and the first transfer pump 23 is used to transfer the silicontetrachloride liquid in the first storage tank 22 to the scrubbing tower8 as a scrubbing solution, and/or, an outlet of the first transfer pump23 is connected with the first cooling separator 2, and the firsttransfer pump 23 is used to transfer the silicon tetrachloride liquid inthe first storage tank 22 to the first cooling separator 2 of thescrubbing tower as a cooling source. In the present example, the firsttransfer pump 23 is a canned motor pump.

Specifically, the methyl chlorosilane preparation device in the presentexample further includes:

a compressor 24, an inlet of the compressor 24 is connected with a gasoutlet of the first cooler 21, an outlet of the compressor 24 isconnected with the third reactor 9, and the compressor 24 is used forcompressing the purified second gas phase products.

It should be noted that the methyl chlorosilane preparation device inthe present example further includes a second cooler 25 and a rectifyingtower 26.

The second cooler 25 is connected with the third reactor 9, and is usedto cool the third gas phase mixture output from the third reactor 9 soas to separate and yield crude methanol;

The rectifying tower 26 is arranged between the second cooler 25 and thefourth reactor 10, and is used for rectifying and purifying the crudemethanol to yield purified third gas phase products. Specifically, aninlet and a gas outlet of the rectification tower 26 are connected withthe second cooler 25 and the fourth reactor 10 respectively, and thecrude methanol is rectified and purified in the rectification tower 26to yield purified third gas phase products. In the present example, thepurification process of the crude methanol in the rectifying tower canbe carried out by a traditional process, which will not be repeatedhere.

In the present example, a gas outlet of the second cooler 25 isconnected with an inlet of the compressor 24. After uncooled gases inthe second cooler 25 are compressed by the compressor, they arecontinued to introduce into the third reactor 9 for reaction.

Specifically, the methyl chlorosilane preparation device in the presentexample further includes a second storage tank 27 and a second transferpump 28.

The second storage tank 27 is arranged between the second cooler 25 andthe rectification tower 26. Specifically, an inlet of the second storagetank 27 is connected with a liquid outlet of the second cooler 25, andan outlet of the second storage tank 27 is connected with an inlet ofthe rectifying tower 26. The second storage tank 27 is used to storecrude methanol;

The second transfer pump 28 is arranged between the second storage tank27 and the rectification tower. Specifically, an inlet of the secondtransfer pump 28 is connected with the second storage tank 27, and anoutlet of the second transfer pump 28 is connected with therectification tower 26. The second transfer pump 28 is used to transfercrude methanol to the rectification tower 26.

It should be noted that the methyl chlorosilane preparation device inthe present example further includes:

a scrubbing and cooling tower 29 connected with the fourth reactor 10,wherein the fourth gas phase mixture enters the scrubbing and coolingtower 29 and uses water as a scrubbing solution for scrubbing andcooling to remove methanol and hydrogen chloride, in the presentexample, the water (i.e., the scrubbing solution) for scrubbing andcooling tower 29 is desalinated water;

a drying tower 30 arranged between the scrubbing and cooling tower 29and the fifth reactor 11, wherein the drying tower 30 is used to dry andremove the by-product dimethyl ether during reaction of water, methanoland hydrogen chloride for generating methyl chlorosilane, so as to yieldpurified fourth gas phase products. Specifically, an inlet of the dryingtower is connected with a gas outlet of the scrubbing and cooling tower,an outlet (gas outlet) of the drying tower 30 is connected with thefifth reactor 11, and the drying tower 30 is provided with a desiccant.In the present example, the desiccant is preferably concentratedsulfuric acid.

Specifically, the methyl chlorosilane preparation device in the presentexample further includes:

a heater 31, wherein an inlet of the heater 31 is connected with a gasoutlet of the drying tower 30, an outlet of the heater 31 is connectedwith the inlet of the fifth reactor 11, and the heater 31 is used toheat the purified fourth gas phase products.

Specifically, the zirconium oxide preparation device in the presentexample further includes:

a beater 32, wherein an inlet of the beater 32 is connected with a solidphase outlet of the first solid-liquid separator 6, and the beater 32 isused to beat the solid separated by the first solid-liquid separator 6,so as to further release the liquid in the solid;

a centrifugal separator 33, wherein an inlet of the centrifugalseparator 33 is connected with an outlet of the beater 32, an outlet ofthe centrifugal separator 33 is connected with an inlet of the secondreactor 7, and the centrifugal separator 33 is used to separate solids(i.e., ZrOCl₂.8H₂O).

It should be noted that, in the present example, a liquid outlet of thefirst solid-liquid separator 6 is connected with an inlet of thehydrolysis tank 3, which is used to allow liquid separated in the firstsolid-liquid separator 6 flowing into the hydrolysis tank 3, so as tosupplement water for hydrolysis, which can reduce the usage amount ofwater for hydrolysis in the hydrolysis tank 3.

It should be noted that the methyl chlorosilane preparation device inthe present example further includes:

a cooling separator 34 on the top of the stripping tower, which isconnected with the tower top of the stripping tower 17. The coolingseparator 34 on the top of the stripping tower is used for cooling andseparating water, and the cooled and separated water flows back into thestripping tower 17, and a gas outlet of the top reboiler of thestripping tower 17 is connected with the fourth reactor 10.Specifically, an inlet of the cooling separator on the top of thestripping tower is connected with a gas outlet of the stripping tower, aliquid outlet of the cooling separator on the top of the stripping toweris connected with an inlet of the tower top of the stripping tower, anda gas inlet of the cooling separator on the top of the stripping toweris connected with the fourth reactor; the cooling separator on the topof the stripping tower is used to cool the separate water, the cooledand separated water flows back into the stripping tower, and thenhydrogen chloride from which the water has been removed flows into thefourth reactor.

As shown in FIG. 3 , an example of the present disclosure provides acombined process for preparing zirconium oxide and methyl chlorosilaneusing the above combined preparation system, and the combined processcomprises the following steps:

(1) Preparation of a first gas phase mixture as an intermediate product:mixing and heating zircon sand, a reducing agent carbon, chlorine gas, aheat supplementing agent silicon and hydrogen chloride, wherein zirconsand, the reducing agent carbon and chlorine gas react to generatezirconium tetrachloride, silicon tetrachloride and carbon monoxide; theheat supplementing agent silicon, chlorine gas and hydrogen chloridereact to generate silicon tetrachloride and hydrogen gas, so as to yielda first gas phase mixture;

wherein, the heating temperature is 1050° to 1200° C., in the presentexample the heating temperature is preferably 1050° C.; the molar ratioof zircon sand to heat supplementing agent silicon is 1:(1.2-1.6). Inthe present example, the molar ratio is preferably 1:1.6 and siliconpowder is preferably used as heat supplementing agent silicon; theamount of reducing agent carbon should be kept in excess, preferablychlorine gas and hydrogen chloride can also be slightly excessive, andthe specific amount can be selected according to the actual situation,which is not further defined in the present example.

Specifically, mixing zircon sand, the reducing agent carbon, chlorinegas, the heat supplementing agent silicon and hydrogen chloride in afirst reactor, 1, and heating the mixture at a heating temperature of1050° C., wherein zircon sand, the reducing agent carbon, and chlorinegas react to generate zirconium tetrachloride, silicon tetrachloride andcarbon monoxide by carbonation and chlorination reaction, and the heatsupplementing agent silicon, chlorine gas and hydrogen chloride react athigh temperature to generate silicon tetrachloride and hydrogen gas, soas to yield the first gas phase mixture; the molar ratio of zircon sandto silicon powder is 1:1.6;

In the present example, the combined process further comprises removinghydrogen chloride and chlorine gas from the first gas phase mixture. Inthe present example, the dechlorinator 35 is used to remove hydrogenchloride and chlorine gas.

Specifically, hydrogen chloride and chlorine gas are removed by passingthe first gas phase mixture through silicon powder in a dechlorinator35.

(2) Preparation of zirconium oxide: cooling the first gas phase mixturefrom which hydrogen chloride and chlorine gas have been removed toseparate a crude zirconium tetrachloride solid; hydrolyzing the crudezirconium tetrachloride solid to generate zirconium oxychloride, so asto yield a hydrolysis mixture; then subjecting the hydrolysis mixture toevaporation, crystallization and solid-liquid separation to yieldzirconium oxychloride solid (the main component is ZrOCl₂.8H₂O); andthen heating and calcining the zirconium oxychloride solid to producezirconium oxide by decomposing;

wherein, water for hydrolyzing the zirconium tetrachloride solidincludes supplemented fresh water, the supplemented fresh water ispreferably desalinated water, and the mass ratio of zirconiumtetrachloride to water for hydrolysis is 1:(3-4). In the presentexample, the mass ratio is preferably 1:3; and evaporating treatmenttemperature for zirconium tetrachloride and water is 85° C. to 100° C.,preferably 85° C.; crystallization treatment temperature is 30° C. to45° C., preferably 30° C.; the temperature at which the zirconiumoxychloride solid is heated and calcined is 800° C. to 1000° C., and thepreferred calcination temperature is 1000° C.; a belt filter, such as avacuum belt filter, is used for solid-liquid separation.

Optionally, the water for hydrolysis in the present example alsoincludes waste water produced in other stages of the combinedpreparation process in the present example, such as low-concentrationacidic waste water produced in the hydrochloric acid stripping processin the stripping tower 17 and liquid phase products produced duringevaporation, crystallization, and solid-liquid separation of thehydrolysis mixture.

In the present example, optionally, before subjecting the hydrolysismixture to evaporation, crystallization, and solid-liquid separation toyield zirconium oxychloride solid, the combined process furthercomprises the following steps: subjecting the hydrolysis mixture tosolid-liquid separation treatment to remove solid impurities. In thepresent example, subjecting the hydrolysis mixture to solid-liquidseparation treatment refers to filtering the hydrolysis mixture in afilter press, and the solid impurities removed by filtration includeunreacted zircon sand and a reducing agent.

Optionally, before heating and calcining the zirconium oxychloridesolid, the combined process further comprises the following steps:beating the zirconium oxychloride solid to release liquid encapsulatedin the zirconium oxychloride solid.

Specifically, the first gas phase mixture from which hydrogen chlorideand chlorine gas have been removed is cooled and separated in the firstcooling separator 2 to separate the crude zirconium tetrachloride solid,and the crude zirconium tetrachloride solid is introduced into thehydrolysis tank 3. Fresh water is supplemented to the hydrolysis tank 3,and the supplemented fresh water is desalinated water, and the water inthe hydrolysis tank 3 includes: the low-concentration acidic waste waterproduced by the hydrochloric acid stripping process in the strippingtower 17 and the filtrate produced by filtering the zirconiumoxychloride crystal slurry. The mass ratio of crude zirconiumtetrachloride to water is 1:3. The crude zirconium tetrachloride ishydrolyzed in the hydrolysis tank 3 to generate zirconium oxychloride,so as to yield a hydrolysis mixture, and then the hydrolysis mixture isfiltered in a filter press (i.e., the second solid-liquid separator 20),to remove solid impurities, wherein the solid impurities includeunreacted zircon sand and a reducing agent;

Then, the hydrolysis mixture from which impurities have been removed isevaporated under a condition of 85° C. in the evaporator 4 to yield aconcentrated solution with a ZrOCl₂ (zirconium oxychloride)concentration greater than 20 mas %, and the concentrated solution iscrystallized in the crystallizer 5 under a condition of 30° C. to yieldZrOCl₂.8H₂O (zirconium oxychloride octahydrate) slurry, thecrystallization slurry is filtered in a vacuum belt filter (i.e., thefirst solid-liquid separator 6) to yield a solid phase, which is afilter cake of ZrOCl₂.8H₂O. The liquid yielded by filtration is returnedand introduced into the hydrolysis tank 3, and the solid-phase filtercake produced by the separation of the first solid-liquid separator 6 isintroduced into the beater 32 for beating, and the filter cake is beatto release liquid encapsulated in the solids during crystallization, soas to yield slurry, and then the slurry is introduced into thecentrifugal separator 33 for centrifugal separation to yield ZrOCl₂.8H₂Oas a product, and the solid zirconium oxychloride is calcined in thesecond reactor 7 at a high temperature, and the second reactor 7 has acalcination temperature of 1000° C. ZrOCl₂.8H₂O is decomposed intozirconium oxide, hydrogen chloride gas and water vapor.

(3) Preparation of a second gas phase mixture as an intermediateproduct: scrubbing the first gas phase mixture from which the crudezirconium tetrachloride solid has been removed, cooling to separate andrecovery silicon tetrachloride therein, so as to yield a second gasphase mixture comprising carbon monoxide and hydrogen gas. In thepresent example, silicon tetrachloride (liquid) is used as a scrubbingsolution for scrubbing.

It should be noted that step (3) also includes further purifying thesecond gas phase mixture, and the specific steps are as follows:introducing the second gas phase mixture into the first cooler 21 tocool and separate the silicon tetrachloride liquid to yield purifiedsecond gas phase products, the separated silicon tetrachloride liquid isthen introduced into the first storage tank 22 for temporary storage.

In the present example, a part of the silicon tetrachloride liquid inthe first storage tank 22 can be used as a cold source (such as the coldsource of the first cooler 2) and/or an scrubbing solution (such as thescrubbing solution of the scrubbing tower 8), and the other part can beused for subsequent processes, such as polycrystalline siliconpreparation processes.

Specifically, scrubbing the first gas phase mixture separated from thecrude zirconium tetrachloride solid in the first cooling separator 2 byusing silicon tetrachloride as a scrubbing solution to recovery silicontetrachloride therein, so as to yield a second gas phase mixturecomprising carbon monoxide and hydrogen gas; introducing the second gasphase mixture into the first cooler 21 to cool and separate the silicontetrachloride liquid, so as to yield purified second gas phase products,and the separated silicon tetrachloride liquid flows into the firststorage tank 22, and transferring a part of the silicon tetrachlorideliquid in the first storage tank 22 to the scrubbing tower 8 through thefirst transfer pump 23 for using as a scrubbing solution, andtransferring the other part to the first cooler 2 through the firsttransfer pump 23 for using as a cold source to cool the first gas phaseproduct, and the remainder flows out for subsequent processes.

(4) Preparation of intermediate product methanol: pressurizing andheating the second gas phase mixture to make reaction and generatemethanol, so as to yield a third gas phase mixture, wherein, thepressurizing pressure is 5.0 MPa to 6.0 MPa, and the heating temperatureis 220° C. to 250° C. In the present example, the pressurizing pressureis preferably 5.0 MPa, and the heating temperature is preferably 220° C.

Further, the molar ratio of carbon to hydrogen in the purified secondgas phase products is 1:(4-5), preferably the molar ratio of carbon tohydrogen is 1:4. Therefore, before subjecting the above-mentionedpurified second gas phase products to pressurize and heat to react togenerate methanol, detecting and adjusting the molar ratio of carbon tohydrogen to achieve the desired range of the molar ratio of carbon tohydrogen.

Specifically, the purified second gas phase mixture is compressed by thecompressor 24, and then introduced into the third reactor 9, and thehydrocarbon detector 15 is used to detect the molar ratio of carbon tohydrogen in the gases introduced into the third reactor 9; the presetmolar ratio of carbon to hydrogen is 1:4; when the detected molar ratioof carbon to hydrogen is greater than a preset molar ratio, the firstvalve 16 on the hydrogen pipeline 14 is opened by the controller tointroduce hydrogen gas into the third reactor 9, until the molar ratioof carbon to hydrogen is equal to the preset molar ratio of carbon tohydrogen, then the first valve 16 is closed by the controller; when thedetected molar ratio of carbon to hydrogen is less than the preset molarratio of carbon to hydrogen, the second valve 40 is closed by thecontroller to reduce amount of hydrogen chloride introduced into thefirst reactor 1, until the molar ratio of carbon to hydrogen is equal tothe preset molar ratio of carbon to hydrogen, the second valve 40 isopened by the controller;

the third reactor 9 has a pressurizing pressure of 5.0 MPa, and aheating temperature of 220° C. The reaction is carried out to producemethanol, so as to yield a third phase mixture.

In the present example, it also includes purifying the third gas phasemixture, which specifically includes the following steps:

introducing the third gas phase mixture produced by the reaction in thethird reactor 9 into the second cooler 25 to cool and separate, so as toyield crude methanol (i.e., the liquid phase product produced bycooling) and gas phase products that is not cooled to liquid phaseproducts. The uncooled liquid products can be returned to be mixed withthe above-mentioned purified second gas phase products, and then enterthe third reactor 9 to react to generate methanol. The crude methanolflows into the second storage tank 27, and then transfers to therectification tower 26 through the second transfer pump 28, and thecrude methanol is rectified and purified by the rectification tower 26.The sewage is discharged from the rectification tower 26 to yieldpurified third gas phase products, and the main component of the thirdgas phase products is methanol

It should be noted that, in the present example, the process conditionsfor purifying crude methanol in the rectifying tower can adopt theexisting traditional process conditions, which will not be repeatedhere.

(5) Preparation of the intermediate product methane chloride: mixing andheating the third gas phase mixture with hydrogen chloride to react togenerate methane chloride and dimethyl ether, so as to yield a fourthgas phase mixture;

wherein, the heating temperature of the third gas phase mixture andhydrogen chloride is 130 to 150° C., preferably 130° C.

In the present example, the combined process further comprises a step ofadding a catalyst, and the catalyst is preferably zinc chloride.

Specifically, introducing the third gas phase mixture into the fourthreactor 10, and introducing hydrogen chloride into the fourth reactor10, and heating in the fourth reactor 10, the heating temperature is130° C., and the catalyst used for the reaction is zinc chloride, and ahydrochlorination reaction occurs to generate methane chloride anddimethyl ether, so as to yield a fourth gas phase mixture.

In the present example, hydrogen chloride introduced into the fourthreactor 10 in step (4) may be additionally introduced hydrogen chloride,or hydrogen chloride extracted from the gas phase products separatedduring preparing zirconium oxide, namely, one or more of the gas phaseproducts produced by evaporation of the hydrolysis mixture in theevaporator 4 and crystallization of the hydrolysis mixture in thecrystallizer 5 are introduced into the stripping tower 17 to striphydrogen chloride, and the stripped hydrogen chloride is purified, andthen passed into the fourth reactor 10 as a source of the requiredhydrogen chloride.

In the present example, the stripping tower 17 has a strippingtemperature of 40° C. to 60° C., and a pressure of 0.1 MPa to 0.3 MPa.In the present example, the stripping tower 17 preferably has astripping temperature of 40° C., and a pressure of 0.3 MPa.

In some optional embodiments, the stripping tower 17 has a tower toptemperature of 40° C. to 60° C. and a tower kettle temperature of 100°C. to 120° C., and a pressure of 20 KPa to 40 KPa.

Specifically, introducing the gas phase products produced by evaporationof the hydrolysis mixture in the evaporator 4 and crystallization of thehydrolysis mixture in the crystallizer 5 into the stripping tower 17 tostripe hydrogen chloride, and the stripping tower 17 has a strippingtemperature of 40° C., and a pressure of 0.3 MPa; introducing hydrogenchloride discharged from the gas phase outlet of the stripping tower 17into the cooling separator 34 on the top of the stripping tower to cooland separate water therein, so as to yield hydrogen chloride gas with apurity greater than 99.9 mas % and a moisture content of less than 1000ppm; allowing water after cooled and separated to flow back into thestripping tower 17, and discharging the waste liquid (mainlylow-concentration waste acid) produced after stripping into thehydrolysis tank 3 as water for hydrolysis; then introducing hydrogenchloride from which water has been removed into the fourth reactor 10 asa source of hydrogen chloride; the combined preparation processaccording to the present example can effectively utilize the acid wastegas and waste liquid generated during preparing zirconium oxide at ahigh value, avoid environmental pollution, reduce the treatment cost ofwaste acid and waste gas, while reduce production cost of methylchlorosilane.

It should be noted that, in the present example, introducing gas phaseproducts produced by evaporation of the hydrolysis mixture in theevaporator 4 into the heat exchanger 18 as a heat source: introducingthe hydrolysis mixture in the hydrolysis tank 3 into the heat exchanger18 for raising temperature by heat exchange, and then the hydrolysismixture after raising temperature by heat exchange is introduced intothe evaporator 4 for evaporation, and then the gas phase productsproduced by evaporating the hydrolysis mixture in the in the evaporator4 are introduced into the heat exchanger 18 for lowering temperature byheat exchange, after that the gas phase products are introduced into thestripping tower 17 for stripping; heating the tower bottoms of thestripping tower 17 by the stripping tower kettle reboiler 19, and makingthe waste liquid in the stripping tower 17 to supplemental flow to thehydrolysis tank 3.

(6) Preparation of methyl chlorosilane: heating the fourth gas phasemixture, and adding silicon powder, making methane chloride in thefourth gas phase mixture to react with the silicon powder to generatemethyl chlorosilane, so as to yield a fifth gas phase mixture, wherein,the heating temperature (that is, the reaction temperature in the fifthreactor) for the fourth gas phase mixture is 280° C. to 320° C.,preferably 280° C. In the present example, a catalyst is added duringthe reaction of methane chloride and silicon powder, and the catalystcan be copper or copper salt, preferably copper.

It should be noted that, in the present example, before subjecting thefourth gas phase mixture to react with silicon powder to generate methylchlorosilane, scrubbing, washing and drying the fourth gas phase mixtureto yield purified fourth gas phase products, Specifically, the combinedprocess include the following steps:

introducing the fourth gas phase mixture into the scrubbing and coolingtower 29, scrubbing and cooling the fourth gas phase mixture by usingwater as a scrubbing solution to remove methanol and hydrogen chloridein the fourth gas phase mixture, and then introducing into drying tower30 for drying to remove water and dimethyl ether, so as to yieldpurified fourth gas phase products. In the present example, the purityof methyl chlorosilane in the purified fourth gas phase products isgreater than 99 mas %.

Specifically, heating the above-mentioned purified fourth gas phasemixture (that is, the purified fourth gas phase products) by the heater31, and then introducing the fourth gas phase mixture into a fifthreactor 11 at a heating temperature of 280° C.; introducing siliconpowder into the fifth reactor 11, heating to make methane chloride reactwith the silicon powder under a condition of copper or copper salt usedas a catalyst to generate methyl chlorosilane, so as to yield a fifthgas phase mixture; the reaction process is exothermic, and heat releasedby the reaction process in the fifth reactor 11 is removed by coolingwater to ensure that the fifth reactor 11 has a temperature of 280° C.;introducing the fifth gas phase mixture into the third cooler 12 to cooland obtain liquid, then introducing the obtained liquid into the thirdstorage tank 13 to store the cooled liquid, said liquid is methylchlorosilane. By rectifying and purifying methyl chlorosilane, dimethyldichlorosilane, methyl trichlorosilane, trimethyl chlorosilane andmethyl dichlorosilane are obtained.

In some optional embodiments, zircon sand in the present example isZrSiO₄, and the molar ratio of the raw materials used isZrSiO₄:C:Cl₂:Si:HCl=1:(4-5):4:(3-4):(12˜16), the mass ratio isZrSiO₄:C:Cl₂:Si:HCl=183:(48˜60):283:(84˜112):(439-583); after zirconsand is subjected to carbonization and chlorination reaction, it ispassed through silicon powder in a dechlorinator 35 to remove hydrogenchloride and chlorine gas, and the resulting product (that is, the firstgas phase mixture) has a composition of: ZrCl=(186-233) kg, CO=(89˜112)kg, SiCl₄=(815˜849) kg, H₂=(12˜16) kg; SiCl₄ (zirconium tetrachloride)is hydrolyzed and calcined to produce zirconium oxide product (98˜123)kg; after the first gas phase mixture is scrubbing and cooling a secondgas phase mixture is produced; after the second gas phase mixture issubjected to cooling, methanolization reaction, cooling andrectification, 81-128 kg of methanol is produced (that is, the purifiedthird gas phase products); the purified third gas phase products aresubjected to hydrochlorination reaction, stripping and drying to produce109-201 kg of methyl chlorosilane (that is, the purified fourth gasphase products); the purified third gas phase products are subjected tohydrochlorination reaction, scrubbing and drying to produce 109-201 kgof methyl chlorosilane (that is, the purified fourth gas phaseproducts); after methyl chlorosilane and silicon powder are subjected tofluidization reaction, cooling and separation, methyl chlorosilaneproduct is produced; after the methyl chlorosilane product is subjectedto rectification and purification treatment 98-361 kg of dimethyldichlorosilane can be produced.

The combined process for preparing zirconium oxide and methylchlorosilane and the combined system in the present examples can realizethe recycling of chlorine, carbon and hydrogen elements, reduce theproduction cost of methane chloride by 50-65%, and reduce the productioncost of methyl chlorosilane (mainly refers to dimethyl dichlorosilane)by 20-35%; at the same time, it can reduce the treatment cost of wastewater and waste gas during preparing zirconium oxide, in turn, furtherreduce the comprehensive preparation cost of zirconium oxide by 10% to15%, and finally avoid greenhouse gas emissions. Specifically, it can bereflected in the following aspects:

TABLE 1 Cost analysis of methanol production from natural gas (yuan/ton)Raw material gases 1050 Electric power 32 Auxiliary material 72.5 Laborcost 4 Depreciation and 212.6 management fees

In step (4), carbon monoxide and hydrogen gas in the tail gases duringpreparing zirconium oxide in steps (1) to (3) are turned into valuablematerials, which not only makes the exhaust gases during preparingzirconium oxide need not be treated, but also makes the exhaust gasessuch as carbon monoxide and hydrogen gas are directly used as rawmaterials for preparing methanol. In the process of preparing methanol,the raw materials carbon monoxide and hydrogen gas account for 80% ofthe cost (as shown in Table 1), so that it can greatly reduce theproduction cost of methanol, thereby reduce the production cost ofpreparing methyl chlorosilane in the subsequent steps (5) and (6).

In addition, in step (2), the waste water and waste gas containinghydrogen chloride are directly used as raw materials for preparingmethyl chlorosilane in the subsequent step (5) through the stripping ofthe stripping tower 17, so that the waste water and waste gas containinghydrogen chloride are turned into valuable materials, which not onlyavoids the treatment cost of waste water and waste gas, but also reducesthe production cost of methyl chlorosilane, thereby reduce theproduction cost of preparing methyl chlorosilane in the subsequent step(6).

In the example of the present disclosure, carbon monoxide and hydrogenchloride generated during preparing zirconium oxide are used as rawmaterials for preparing methyl chlorosilane, so that both waste gasesand silicon tetrachloride can be effectively recycled with high value,which reduces the treatment cost of waste gases and silicontetrachloride, avoids environmental pollution, reduces the productioncost of methyl chlorosilane and polycrystalline silicon, and improvesthe technological level as well as the comprehensive economic benefits.

Example 3

As shown in FIG. 2 , the example of the present disclosure provides acombined system for preparing zirconium oxide and methyl chlorosilane,and the difference from the combined system in Example 2 is that: thedechlorinator 35 is arranged between the first reactor 1 and the firstcooling separator 2, an inlet of the dechlorinator 35 is connected withan outlet of the first reactor 1, and an outlet of the dechlorinator 35is connected with the first cooling separator 2.

The example of the present disclosure also provide a combined processfor preparing zirconium oxide and methyl chlorosilane using the abovecombined system, and the difference from the combined process in example2 is that:

in step (1), first reactor 1 has a heating temperature of 1200° C., andthe molar ratio of zircon sand to silicon powder is 1:1.3;

in step (2), the mass ratio of crude zirconium tetrachloride to water is1:4, the evaporator 5 has a temperature of 100° C., the crystallizer hasa temperature of 40° C., and the second reactor 7 has a high-temperaturecalcination temperature of 800° C.; in step (4), the preset molar ratioof carbon to hydrogen is 1:5, the third reactor 9 has a pressurizationpressure of 6.0 MPa, and a heating temperature of 250° C.;

in step (5), the fourth reactor 10 has a heating temperature of 140° C.;the stripping tower 17 has a stripping temperature of 50° C., and apressure of 0.1 MPa;

in step (6), the fifth reactor 11 has a heating temperature of 320° C.

Example 4

The example of the present disclosure provides a combined process forpreparing zirconium oxide and methyl chlorosilane using the combinedsystem in Example 2, and the difference from the process in Example 2 isthat:

in step (1), the first reactor 1 has a heating temperature of 1100° C.,and the molar ratio of zircon sand to silicon powder is 1:1.4;

in step (2), the mass ratio of crude zirconium tetrachloride to water is1:3.5, the evaporator 5 has a temperature of 95° C., the crystallizerhas a temperature of 45° C., and the second reactor 7 has ahigh-temperature calcination temperature of 900° C.;

in step (4), the preset molar ratio of carbon to hydrogen is 1:4.5, thethird reactor 9 has a pressurization pressure of 5.5 MPa, and a heatingtemperature of 235° C.;

in step (5), the fourth reactor 10 has a heating temperature of 150° C.;the stripping tower 17 has a stripping temperature of 60° C., and apressure of 0.2 MPa;

in step (6), the fifth reactor 11 has a heating temperature of 300° C.

Example 5

An example of the present disclosure provides a combined system forpreparing zirconium oxide, methyl chlorosilane and polycrystallinesilicon, wherein the system includes the combined system for preparingzirconium oxide and methyl chlorosilane according to Example 1, andfurther includes:

a polycrystalline silicon preparation device which is connected with thezirconium oxide preparation device and is used for preparingpolycrystalline silicon by using the silicon tetrachloride separated bythe zirconium oxide preparation device as a raw material.

The example of the present disclosure also provide a combined processfor preparing zirconium oxide, methyl chlorosilane, and polycrystallinesilicon using the above-mentioned combined system for preparingzirconium oxide, methyl chlorosilane, and polycrystalline silicon,comprising:

adopting the liquid phase products separated during the combined processfor preparing zirconium oxide and methyl chlorosilane according toExample 1, said liquid phase products comprise silicon tetrachloride,and said silicon tetrachloride is used as a raw material to preparepolycrystalline silicon. Specifically, the steps are as follows

using the silicon tetrachloride liquid phase products separated duringthe combined process as a raw material to prepare polycrystallinesilicon, which comprises firstly performing a hydrochlorination withsilicon tetrachloride to produce trichlorosilane, and then performing ahydrogen reduction reaction with the trichlorosilane to producepolycrystalline silicon.

In the example of the present disclosure, not only carbon monoxide andhydrogen chloride generated during preparing zirconium oxide are used asraw materials for preparing methyl chlorosilane, but also silicontetrachloride, a by-product generated during preparing zirconium oxide,is used as a raw material for preparing polycrystalline silicon, so thatboth waste gases and silicon tetrachloride can be effectively recycledwith high value, which reduces the treatment cost of waste gases and theby-product silicon tetrachloride, avoids environmental pollution,reduces the production cost of methyl chlorosilane and polycrystallinesilicon, and improves the technological level as well as thecomprehensive economic benefits.

Example 6

An example of the present disclosure provides a combined system forpreparing zirconium oxide, methyl chlorosilane and polycrystallinesilicon used in a combined process for preparing zirconium oxide, methylchlorosilane and polycrystalline silicon, the system includes thecombined system for preparing zirconium oxide and methyl chlorosilaneaccording to the Example 2 or Example 3, and the zirconium oxidepreparation device of the present example is also used to separatesilicon tetrachloride during preparing zirconium oxide.

As shown in FIG. 1 or FIG. 2 , the combined system for preparingzirconium oxide, methyl chlorosilane and polycrystalline silicon in thepresent example further includes:

a polycrystalline silicon preparation device (not shown in the figure)which is connected with the zirconium oxide preparation device and isused for preparing polycrystalline silicon by using the silicontetrachloride separated by the zirconium oxide preparation device as araw material.

Furthermore, the polycrystalline silicon preparation device includes ahydrochlorination reactor, a rectification and purification unit, and aCVD reduction furnace (CVD, that is, chemical vapor deposition).

The hydrochlorination reactor, preferably a fluidized bed reactor, isconnected with the zirconium oxide preparation device, such as connectedwith the first storage tank 20, and is used for making the by-productsilicon tetrachloride produced by the zirconium oxide preparation devicewith silicon powder, hydrogen gas, hydrogen chloride undergoing ahydrochlorination reaction to generate trichlorosilane.

The rectification and purification unit includes a plate rectificationtower and a packed rectification tower, wherein the plate rectificationtower is connected with a hydrochlorination reactor, and is used toremove silicon tetrachloride in the mixture solution of trichlorosilaneand silicon tetrachloride generated in the hydrochlorination reactor,and high-boiling metal impurities, wherein the high-boiling point metalimpurities include aluminum chloride, ferric chloride, calcium chloride,etc.; the packing rectification tower is connected with the platerectification tower, which is used to purify trichlorosilane liquid fromwhich silicon tetrachloride and high-boiling point metal impurities havebeen removed in the plate rectification tower, so as to further removedichlorodihydrosilicon and the metal impurities such as phosphoruschloride and boron chloride in the trichlorosilane liquid to producepurified trichlorosilane.

The CVD reduction furnace is connected with the packing rectificationtower, and is used for performing chemical vapor deposition reaction onpurified trichlorosilane with hydrogen gas under a condition of heatingto reduce trichlorosilane to polycrystalline silicon. CVD furnace mayhave a heating temperature of 1000° C. to 1100° C., and in the presentexample, CVD furnace preferably have a heating temperature of 1080° C.

It should be noted that, in the present example, the polycrystallinesilicon preparation device may also use a traditional process method,such as a Siemens process or a modified Siemens process device, and thesimilarities will not be repeated one by one.

The example of the present disclosure also provide a combined processfor preparing zirconium oxide, methyl chlorosilane, and polycrystallinesilicon using the above-mentioned combined system for preparingzirconium oxide, methyl chlorosilane, and polycrystalline silicon, inaddition to comprise steps (1) to (6) according to Example 3, theprocess further comprises step (7):

(7) Preparing polycrystalline silicon: using the silicon tetrachlorideliquid phase products separated during preparing zirconium oxide as araw material to prepare polycrystalline silicon, which comprises firstlyperforming a hydrochlorination with said silicon tetrachloride toproduce trichlorosilane, and then performing a hydrogen reductionreaction with the trichlorosilane to produce polycrystalline silicon.

Specifically, using the silicon tetrachloride separated in step (3) as araw material, and introducing into the polycrystalline siliconpreparation device to prepare polycrystalline silicon, that is, firstly,introducing silicon tetrachloride into the hydrochlorination reactor asa raw material, and then adding silicon powder, hydrogen gas, hydrogenchloride and other raw materials, making the above raw materials undergohydrochlorination reaction to produce trichlorosilane; then introducingthe silicon trichloride into the plate purification tower and the packedrectification tower successively for purification to produce purifiedtrichlorosilane; after that, introducing the purified trichlorosilaneinto the CVD reduction furnace, and feeding hydrogen gas, so that thetrichlorosilane and the hydrogen undergo a reduction reaction to yieldpolycrystalline silicon.

It should be noted that, in the present example, the process forpreparing polycrystalline silicon is preferably performed by usingSiemens method or modified Siemens method, and the specific processparameters and the same steps will not be repeated here.

In the example of the present disclosure, not only carbon monoxide andhydrogen chloride generated during preparing zirconium oxide are used asraw materials for preparing methyl chlorosilane, but also silicontetrachloride, a by-product generated during preparing zirconium oxide,is used as a raw material for preparing polycrystalline silicon, so thatboth waste gases and the by-product silicon tetrachloride can beeffectively recycled with high value, which reduces the treatment costof waste gases and silicon tetrachloride, avoids environmentalpollution, reduces the production cost of methyl chlorosilane andpolycrystalline silicon, and improves the technological level as well asthe comprehensive economic benefits.

Example 7

An Example of the present disclosure provides a combined system forpreparing zirconium oxide and polycrystalline silicon, the systemincludes:

a zirconium oxide preparation device, which is used to prepare zirconiumoxide with zircon sand, a reducing agent carbon, chlorine gas, a heatsupplementing agent silicon and hydrogen chloride as raw materials, andthe zirconium oxide preparation device is also used to separate gasphase products of carbon monoxide, hydrogen gas and hydrogen chlorideproduced during preparing zirconium oxide;

a polycrystalline silicon preparation device, which is connected withsaid zirconium oxide preparation device and is used for preparingpolycrystalline silicon by using the silicon tetrachloride separated bysaid zirconium oxide preparation device as a raw material.

It should be noted that the zirconium oxide preparation device in thepresent example adopts the same device as the zirconium oxidepreparation device in Example 6, and the details are not repeated here.The waste gases such as carbon monoxide and hydrogen chloride separatedfrom the zirconium oxide preparation device can be used for subsequentprocesses, such as the preparation of methyl chlorosilane.

It should be noted that, the polycrystalline silicon preparation devicein the present example adopts the same device as the polycrystallinesilicon preparation device in example 6, and the details are notrepeated here.

The example of the present disclosure also provide a combined processfor preparing zirconium oxide and polycrystalline silicon using theabove-mentioned combined system for preparing zirconium oxide andpolycrystalline silicon, the process comprises:

preparing zirconium oxide by using zircon sand, a reducing agent carbon,chlorine gas, a heat supplementing agent silicon and hydrogen chlorideas raw materials, wherein liquid phase products separated duringpreparing zirconium oxide include silicon tetrachloride; and

preparing polycrystalline silicon by using the separated liquid phaseproducts during preparing zirconium oxide as the raw materials.

It should be noted that the processes for preparing zirconium oxide andpolycrystalline silicon in the present example are the same as thoseprocesses in Example 6, which will not be repeated here.

In the example of the present disclosure, silicon tetrachloride, aby-product generated during preparing zirconium oxide, is used as a rawmaterial for preparing polycrystalline silicon, so that the by-productsilicon tetrachloride can be effectively recycled with high value, whichreduces the treatment cost of the by-product, and further reduces theproduction cost of polycrystalline silicon, and improves thetechnological level as well as the comprehensive economic benefits.

It can be understood that the above embodiments are merely exemplaryimplementations used to illustrate the principle of the presentinvention, but the present invention is not limited thereto. For thoseskilled in the art, various variations and modifications can be madewithout departing from the spirit and essence of the present invention,and these variations and modifications are also within the protectionscope of the present invention.

What is claimed is:
 1. A combined process for preparing zirconium oxideand methyl chlorosilane, comprising: preparing zirconium oxide by usingzircon sand, carbon as a reducing agent, chlorine gas, silicon as a heatsupplementing agent and hydrogen chloride as raw materials, whereinproducts separated during preparing zirconium oxide include gas phaseproducts and liquid phase products, and said gas phase products includecarbon monoxide, hydrogen gas and hydrogen chloride; and preparingmethyl chlorosilane by using the separated gas phase products duringpreparing zirconium oxide as raw materials.
 2. The combined process forpreparing zirconium oxide and methyl chlorosilane according to claim 1,wherein the combined process specifically comprises the following steps:mixing and heating zircon sand, the reducing agent carbon, chlorine gas,the heat supplementing agent silicon and hydrogen chloride in a firstreactor, wherein zircon sand, the reducing agent carbon and chlorine gasreact to generate zirconium tetrachloride, silicon tetrachloride andcarbon monoxide; the heat supplementing agent silicon, chlorine gas andhydrogen chloride react to generate silicon tetrachloride and hydrogengas, so as to yield a first gas phase mixture; removing hydrogenchloride and chlorine gas from the first gas phase mixture by passingthe first gas phase mixture through silicon powder in a dechlorinator;cooling the first gas phase mixture from which hydrogen chloride andchlorine gas have been removed to separate a crude zirconiumtetrachloride solid; hydrolyzing the crude zirconium tetrachloride solidto generate zirconium oxychloride, so as to yield a hydrolysis mixture;then subjecting the hydrolysis mixture to evaporation, crystallizationand solid-liquid separation to yield solid zirconium oxychloride; andheating the solid zirconium oxychloride in a second reactor to yieldzirconium oxide; scrubbing the first gas phase mixture from which thecrude zirconium tetrachloride solid has been removed by using silicontetrachloride as a scrubbing solution to recovery silicon tetrachloridetherein, so as to yield a second gas phase mixture comprising carbonmonoxide and hydrogen gas; introducing the second gas phase mixture intoa third reactor; pressurizing and heating to make reaction and generatemethanol, so as to yield a third gas phase mixture; introducing thethird gas phase mixture into a fourth reactor, and introducing hydrogenchloride into the fourth reactor, heating to make methanol react withhydrogen chloride to generate methane chloride, so as to yield a fourthgas phase mixture; introducing the fourth gas phase mixture into a fifthreactor, and introducing silicon powder into the fifth reactor, heatingto make methane chloride react with the silicon powder to generatemethyl chlorosilane, so as to yield a fifth gas phase mixture.
 3. Thecombined process for preparing zirconium oxide and methyl chlorosilaneaccording to claim 2, wherein the combined process further comprises thefollowing steps: detecting a molar ratio of carbon to hydrogen in thegases introduced into the third reactor by a hydrocarbon detector, whena detected molar ratio of carbon to hydrogen is greater than a presetmolar ratio of carbon to hydrogen, hydrogen gas is introduced into thethird reactor, until the molar ratio of carbon to hydrogen in the gasesintroduced into the third reactor is equal to the preset molar ratio ofcarbon to hydrogen; when the detected molar ratio of carbon to hydrogenis less than the preset molar ratio of carbon to hydrogen, amount ofhydrogen chloride introduced into a first reactor is reduced, until themolar ratio of carbon to hydrogen in the gases introduced into the thirdreactor is equal to the preset molar ratio of carbon to hydrogen.
 4. Thecombined process for preparing zirconium oxide and methyl chlorosilaneaccording to claim 3, wherein the preset molar ratio of carbon tohydrogen is 1:4 to 1:5.
 5. The combined process for preparing zirconiumoxide and methyl chlorosilane according to any one of claims 2 to 4,wherein the third reactor has a pressure of 5.0 MPa to 6.0 MPa, and aheating temperature of 220° C. to 250° C.
 6. The combined process forpreparing zirconium oxide and methyl chlorosilane according to any oneof claims 2 to 4, wherein the combined process further comprises thefollowing steps: introducing one or more of the gas phase productsproduced by evaporation of the hydrolysis mixture and crystallization ofthe hydrolysis mixture into a stripping tower to stripe hydrogenchloride, and then the hydrogen chloride stripped is used as a source ofhydrogen chloride for introducing into the fourth reactor.
 7. Thecombined process for preparing zirconium oxide and methyl chlorosilaneaccording to claim 6, wherein said stripping tower has a strippingtemperature of 40° C. to 60° C., and a pressure of 0.1 MPa to 0.3 MPa.8. The combined process for preparing zirconium oxide and methylchlorosilane according to claim 6, wherein the combined process furthercomprises the following steps: introducing gas phase products producedby evaporation of the hydrolysis mixture into a heat exchanger as a heatsource: introducing the hydrolysis mixture into the heat exchanger forraising temperature by heat exchange, then evaporating the hydrolysismixture after raising temperature by heat exchange; introducing the gasphase products produced by evaporating the hydrolysis mixture into theheat exchanger for lowering temperature by heat exchange, after thatintroducing the gas phase products into the stripping tower forstripping.
 9. The combined process for preparing zirconium oxide andmethyl chlorosilane according to claim 6, wherein the combined processfurther comprises the following steps: cooling hydrogen chloridedischarged from a gas phase outlet of the stripping tower to separatewater therein, and introducing hydrogen chloride from which water hasbeen removed into the fourth reactor.
 10. The combined process forpreparing zirconium oxide and methyl chlorosilane according to any oneof claims 2 to 4, 7, 8, and 9, wherein, before subjecting the hydrolysismixture to evaporation, crystallization, and solid-liquid separation toyield solid zirconium oxychloride, the combined process furthercomprises the following steps: subjecting the hydrolysis mixture tosolid-liquid separation to remove solid impurities therein.
 11. Thecombined process for preparing zirconium oxide and methyl chlorosilaneaccording to any one of claims 2 to 4, 7, 8, and 9, wherein, beforeintroducing the second gas phase mixture into the third reactor, thecombined process further comprises the following steps: cooling thesecond gas phase mixture to separate silicon tetrachloride liquid, so asto yield purified second gas phase products.
 12. The combined processfor preparing zirconium oxide and methyl chlorosilane according to claim11, wherein the combined process further comprises the following steps:using the silicon tetrachloride liquid separated by cooling the secondgas phase mixture as a cold source for the step of cooling to separatethe crude zirconium tetrachloride solid from the first gas phasemixture; and/or, using the silicon tetrachloride liquid separated bycooling the second gas phase mixture as a scrubbing solution for thestep of scrubbing the first gas phase mixture, from which silicontetrachloride has been separated, so as to remove silicon tetrachloridetherein.
 13. The combined process for preparing zirconium oxide andmethyl chlorosilane according to any one of claims 2 to 4, 7, 8, 9, and12, wherein, before introducing the third gas phase mixture into thefourth reactor, the combined process further comprises the followingsteps: cooling the third gas phase mixture to yield crude methanol, andpurifying the crude methanol by rectification to yield purified thirdgas phase products.
 14. The combined process for preparing zirconiumoxide and methyl chlorosilane according to any one of claims 2 to 4, 7,8, 9, and 12, wherein, before introducing the fourth gas phase mixtureinto the fifth reactor, the combined process further comprises thefollowing steps: scrubbing and cooling the fourth gas phase mixture byusing water as a scrubbing solution to remove methanol and hydrogenchloride, and then drying to remove water, so as to yield purifiedfourth gas phase products.
 15. The combined process for preparingzirconium oxide and methyl chlorosilane according to any one of claims 2to 4, 7, 8, 9, and 12, wherein the first reactor has a heatingtemperature of 1050° C. to 1200° C., and/or the second reactor has aheating temperature of 800° C. to 1000° C.
 16. The combined process forpreparing zirconium oxide and methyl chlorosilane according to any oneof claims 2 to 4, 7, 8, 9, and 12, wherein the fourth reactor has aheating temperature of 130° C. to 150° C.
 17. The combined process forpreparing zirconium oxide and methyl chlorosilane according to any oneof claims 2 to 4, 7, 8, 9, and 12, wherein the fifth reactor has aheating temperature of 280° C. to 320° C.
 18. The combined process forpreparing zirconium oxide and methyl chlorosilane according to any oneof claims 2 to 4, 7, 8, 9, and 12, wherein, the combined process furthercomprises the following steps: returning liquid produced by evaporation,crystallization and solid-liquid separation of the hydrolysis mixture tothe hydrolysis mixture which is produced by hydrolyzing the crudezirconium tetrachloride solid to generate zirconium oxychloride, andthen subjecting the hydrolysis mixture to evaporation, crystallizationand solid-liquid separation.
 19. A combined process for preparingzirconium oxide, methyl chlorosilane and polycrystalline silicon,wherein said liquid phase products separated during the combined processfor preparing zirconium oxide and methyl chlorosilane according to claim1 comprises silicon tetrachloride, and said silicon tetrachloride isused as a raw material to prepare polycrystalline silicon.
 20. Thecombined process for preparing zirconium oxide, methyl chlorosilane andpolycrystalline silicon according to claim 19, wherein, the combinedprocess for preparing zirconium oxide and methyl chlorosilane accordingto any one of claims 2 to 4, 7, 8, 9, and 12 further comprises thefollowing steps: using said silicon tetrachloride liquid phase productsseparated during preparing zirconium oxide as a raw material to preparepolycrystalline silicon, which comprises firstly performing ahydrochlorination with said silicon tetrachloride to yieldtrichlorosilane, and then performing a hydrogen reduction reaction withthe trichlorosilane to yield polycrystalline silicon.
 21. A system usedfor the combined process for preparing zirconium oxide and methylchlorosilane according to any one of claims 1 to 18, including: azirconium oxide preparation device, which is used to prepare zirconiumoxide with zircon sand, a reducing agent carbon, chlorine gas, a heatsupplementing agent silicon and hydrogen chloride as raw materials, andis also used to separate gas phase products of carbon monoxide, hydrogengas and hydrogen chloride produced during preparing zirconium oxide; amethyl chlorosilane preparation device, which is connected with saidzirconium oxide preparation device, and is used to prepare methylchlorosilane with gas phase products of carbon monoxide, hydrogen gasand hydrogen chloride separated from said zirconium oxide preparationdevice as raw materials.
 22. The system used for the combined processfor preparing zirconium oxide and methyl chlorosilane according to claim21, wherein, the zirconium oxide preparation device includes a firstreactor, a dechlorinator, a first cooling separator, a hydrolysis tank,an evaporator, a crystallizer, a first solid-liquid separator, a secondreactor, and a scrubbing tower, the methyl chlorosilane preparationdevice includes a third reactor, a fourth reactor, and a fifth reactor;said first reactor is used to mix and heat zircon sand, a reducing agentcarbon, chlorine gas, a heat supplementing agent silicon, and hydrogenchloride, allow zircon sand, the reducing agent carbon, and chlorine gasto react to generate zirconium tetrachloride, silicon tetrachloride andcarbon monoxide; and allow the heat supplementing agent silicon,chlorine gas, hydrogen chloride to react to generate silicontetrachloride, hydrogen gas, so as to yield a first gas phase mixture;said dechlorinator is arranged between said first reactor and said firstcooling separator, and said dechlorinator is connected with said firstreactor and said first cooling separator, respectively; alternatively,said dechlorinator is arranged in said first reactor, and separates afirst reaction chamber provided in the first reactor from an outlet ofthe first reactor, and the dechlorinator is used to remove chlorine gas,hydrogen chloride in the first gas phase mixture by using silicon powertherein; said first cooling separator is connected with said firstreactor, and is used to cool the introduced first gas phase mixture fromwhich hydrogen chloride and chlorine have been removed, so as toseparate the crude zirconium tetrachloride solid and produce the firstgas phase mixture without crude zirconium tetrachloride solid; saidhydrolysis tank is connected with said first cooling separator, and saidcrude zirconium tetrachloride solid is introduced into the hydrolysistank and then is hydrolyzed to generate zirconium oxychloride, so as toyield a hydrolysis mixture; said evaporator is connected with saidhydrolysis tank, and said hydrolysis mixture is introduced into theevaporator for evaporation; said crystallizer is connected with saidevaporator, and the hydrolysis mixture after evaporation is introducedinto the crystallizer for crystallization; said first solid-liquidseparator is connected with said crystallizer, and the hydrolysismixture after crystallization is introduced into the first solid-liquidseparator for solid-liquid separation, so as to yield solid zirconiumoxychloride; said second reactor is connected with said firstsolid-liquid separator, and solid zirconium oxychloride is introducedinto the second reactor and heated to yield zirconium oxide; saidscrubbing tower is connected with said first cooling separator, and thefirst gas phase mixture from which the crude zirconium tetrachloridesolid has been removed is scrubbed by using silicon tetrachloride as ascrubbing solution to recovery silicon tetrachloride liquid, so as toyield a second gas phase mixture comprising carbon monoxide and hydrogengas; said third reactor is connected with said scrubbing tower, and saidsecond gas phase mixture is introduced into the third reactor, and ispressurized and heated to make react and generate methanol, so as toyield a third gas phase mixture; said fourth reactor is connected withsaid third reactor, said third gas phase mixture is introduced into thefourth reactor; hydrogen chloride is introduced into the fourth reactor;and both of them is heated to make methanol react with hydrogen chlorideand to generate methane chloride, so as to yield a fourth gas phasemixture; said fifth reactor is connected with said fourth reactor, saidfourth gas phase mixture is introduced into the fifth reactor, siliconpowder is introduced into the fifth reactor, and both of them is heatedto make methane chloride react with silicon powder and to generatemethyl chlorosilane, so as to yield a fifth gas phase mixture.
 23. Thesystem used for the combined process for preparing zirconium oxide andmethyl chlorosilane according to claim 22, wherein said methylchlorosilane preparation device further includes: a hydrogen pipelineconnected with an inlet of said third reactor, wherein said hydrogenpipeline is used for introducing hydrogen gas into the third reactor,and said hydrogen pipeline is provided with a first valve; a hydrogenchloride pipeline connected with an inlet of said first reactor, whereinsaid hydrogen chloride pipeline is used for introducing hydrogenchloride into the first reactor, and said hydrogen chloride pipeline isprovided with a second valve; a hydrocarbon detector for detecting themolar ratio of carbon to hydrogen in the gases introduced into saidthird reactor; a controller for receiving a molar ratio value of carbonto hydrogen in the gases in said third reactor detected by saidhydrocarbon detector, when the molar ratio of carbon to hydrogendetected by the hydrocarbon detector is greater than a preset molarratio of carbon to hydrogen, the controller open the first valve tointroduce hydrogen gas into the third reactor, until the detected molarratio of carbon to hydrogen is equal to the preset molar ratio of carbonto hydrogen, and then the controller close the first valve; when themolar ratio of carbon to hydrogen detected by the hydrocarbon detectoris less than the preset molar ratio of carbon to hydrogen, thecontroller close the second valve to reduce the amount of hydrogenchloride introduced into a first reactor, until the detected molar ratioof carbon to hydrogen is equal to the preset molar ratio of carbon tohydrogen, and then the controller open the second valve.
 24. The systemused for the combined process for preparing zirconium oxide and methylchlorosilane according to claim 22 or 23, wherein said methylchlorosilane preparation device further includes: a stripping tower,wherein a gas outlet of said stripping tower is connected with the inletof said fourth reactor, an inlet of said stripping tower is connectedwith said evaporator, and gas phase products evaporated by theevaporator is introduced into the stripping tower to strip hydrogenchloride, and the stripped hydrogen chloride is introduced into saidfourth reactor as a source of hydrogen chloride; and/or, the inlet ofsaid stripping tower is connected with said crystallizer, and gas phaseproducts crystallized by the crystallizer is introduced into thestripping tower to strip hydrogen chloride, and the stripped hydrogenchloride is introduced into said fourth reactor as a source of hydrogenchloride.
 25. The system used for the combined process for preparingzirconium oxide and methyl chlorosilane according to claim 24, whereinsaid methyl chlorosilane preparation device further includes: a heatexchanger, which is connected with said stripping tower and alsoconnected with said evaporator, and the gas phase products produced byevaporating the hydrolysis mixture through the evaporator is introducedinto the heat exchanger as a heat source, and the hydrolysis mixture isintroduced into the heat exchanger for raising temperature by heatexchange, and then the gas phase products produced by evaporating thehydrolysis mixture are introduced into the heat exchanger for loweringtemperature by heat exchange, after that the gas phase products areintroduced into the stripping tower for stripping.
 26. The system usedfor the combined process for preparing zirconium oxide and methylchlorosilane according to claim 24, wherein said methyl chlorosilanepreparation device further includes: a cooling separator on the top ofthe stripping tower, wherein an inlet of the cooling separator on thetop of the stripping tower is connected with the gas outlet of thestripping tower, a liquid outlet of the cooling separator on the top ofthe stripping tower is connected with the inlet on the top of thestripping tower, and a gas outlet of the cooling separator on the top ofthe tower is connected with said fourth reactor, and the coolingseparator on the top of the stripping tower is used for cooling andseparating water, and the cooled and separated water flows back into thestripping tower, and hydrogen chloride from which water has been removedflows into the fourth reactor.
 27. The system used for the combinedprocess for preparing zirconium oxide and methyl chlorosilane accordingto any one of claims 22, 23, 25, and 26, wherein said zirconium oxidepreparation device further includes: a second solid-liquid separator,wherein an inlet of said second solid-liquid separator is connected withan outlet of said hydrolysis tank, an outlet of the second solid-liquidseparator is connected with an inlet of said evaporator, and thehydrolysis mixture through the hydrolysis tank is introduced into thesecond solid-liquid separator for performing solid-liquid separation toremove solid impurities, and then flows into the evaporator.
 28. Thesystem used for the combined process for preparing zirconium oxide andmethyl chlorosilane according to any one of claims 22, 23, 25, and 26,wherein said zirconium oxide preparation device further includes: afirst cooler, which is arranged between said scrubbing tower and saidthird reactor, wherein an inlet of said first cooler is connected with agas outlet of the scrubbing tower, a gas outlet of the first cooler isconnected with an inlet of the third reactor, and the first cooler isused for cooling the second gas phase mixture to separate the silicontetrachloride liquid, so as to yield purified second gas phase products.29. The system used for the combined process for preparing zirconiumoxide and methyl chlorosilane according to claim 28, wherein a liquidoutlet of said first cooler is connected with the inlet of said firstcooling separator, and the silicon tetrachloride liquid separated fromthe second gas phase mixture is introduced into the first coolingseparator as a cold source to cool the first gas phase mixture, so as toseparate the crude zirconium tetrachloride solid; and/or, a liquidoutlet of said first cooler is connected with an inlet of the scrubbingtower, and the silicon tetrachloride liquid separated by cooling thesecond gas phase mixture is introduced into the scrubbing tower forscrubbing to recover silicon tetrachloride.
 30. The system used for thecombined process for preparing zirconium oxide and methyl chlorosilaneaccording to any one of claims 22, 23, 25, 26, and 29, wherein saidmethyl chlorosilane preparation device further includes: a second coolerconnected with said third reactor, wherein the third gas phase mixtureenters said second cooler for cooling to yield crude methanol; arectification tower arranged between said second cooler and said fourthreactor, wherein the rectification tower is connected with the secondcooler and the fourth reactor respectively, and crude methanol isintroduced into the rectification tower for purification to yieldpurified third gas phase products.
 31. The system used for the combinedprocess for preparing zirconium oxide and methyl chlorosilane accordingto any one of claims 22, 23, 25, 26, and 29, wherein said methylchlorosilane preparation device further includes: a scrubbing andcooling tower connected with said fourth reactor, wherein the fourth gasphase mixture is entered into said scrubbing and cooling tower and wateris used as a scrubbing solution for scrubbing and cooling to removemethanol and hydrogen chloride; a drying tower arranged between saidscrubbing and cooling tower and said fifth reactor, wherein the dryingtower is used to dry and remove a by-product dimethyl ether duringreaction of water, methanol and hydrogen chloride for generating methylchlorosilane, so as to yield purified fourth gas phase products.
 32. Thesystem used for the combined process for preparing zirconium oxide andmethyl chlorosilane according to any one of claims 22, 23, 25, 26, and29, wherein a liquid outlet of said first solid-liquid separator isconnected with an inlet of said hydrolysis tank, and the liquid in thefirst solid-liquid separator flows into the hydrolysis tank.
 33. Asystem used for the combined process for preparing zirconium oxide,methyl chlorosilane and polycrystalline silicon according to claim 19 or20, wherein, besides the system used for the combined process forpreparing zirconium oxide and methyl chlorosilane according to any oneof claims 21, 22, 23, 25, 26, 29, it further includes: a polycrystallinesilicon preparation device, which is connected with said zirconium oxidepreparation device and is used for preparing polycrystalline silicon byusing the silicon tetrachloride separated by said zirconium oxidepreparation device as a raw material.